Knowledge Management System Of Institute of process engineering,CAS
|Thesis Advisor||赵国英, 蒋元力|
离子液体（ILs）作为一种平台化合物，由于其优异性能在诸多领域凸显优势，是绿色技术革命的重要研究方向之一。但蓬勃发展的离子液体市场及产业化应用及对离子液体合成工艺及纯度提出了更高的要求。开发三维可视化原位监测技术对离子液体合成过程进行实时监控，获得动力学特征以及流体传质规律是实现关键设备优化设计和过程精确调控的关键。然而近年来不断涌出的过程分析监测技术，大多不能提供反应体系空间信息。本论文旨在提供一种新的便捷、无损、快速原位监控离子液体合成过程的分析技术。主要研究内容如下：（1）系统测定了咪唑、吡啶、卤代烷烃以及相应离子液体的弛豫特性T1/T2，确定低场核磁共振成像技术作为离子液体合成过程原位研究的分析工具。以[C4mim]Br合成为例，根据反应体系组分的核磁共振弛豫特性，建立两组分定性定量分析方法，并利用原位红外实验验证新建方法的可行性和准确性。（2）采用低场核磁共振成像技术原位研究[C4mim]Br合成过程，结果表明，随着咪唑和溴丁烷初始摩尔比越大、反应温度越高、搅拌速度越快，则合成速率越快或所需时间越短。计算获得不同温度下的二级动力学速率常数k（0.042~1.378 mol-1·L·h-1）和表观活化能EA（72 kJ/mol）与文献报道相一致。在32℃，1:1.2摩尔比下对[C4mim]Br合成过程采集T1加权像，发现整个体系在离子液体收率40 mol%时发生相分离并经过相聚并和翻转，离子液体从上层沉积到反应器底部。（3）采用低场核磁共振成像技术系统考察了卤代烷烃链长、卤元素种类以及叔胺碱性对叔胺/卤代烃烷基化合成离子液体过程的影响规律。结果表明，烷基碳链链越长，合成速率越慢；卤代烷烃的卤元素电负性越大，离子液体合成速率越快，如BuI>BuBr>BuCl；叔胺的碱性对合成速率也有较大影响，比如[C4py]Br合成速率远小于[C4mim]Br，其速率常数分别0.047和0.807 (mol/L)-1·h-1。;Ionic liquids (ILs), as a platform compound, have exhibited excellent performance in fields due to their outstanding and unique properties, and is one of the important research topics under the green technology revolution. However, the increasing market and industrial application of ionic liquids have boosted the production cost and quality of the ionic liquids. The development of three-dimensional visualization in-situ monitoring technology to study the kinetic characteristics and reaction transfer laws of the synthesis process of ionic liquids is the key to the optimization design of key equipment and precise control of the process. However, most of the current in-situ process analysis technologies cannot provide spatial information about the reaction system. This paper aims to provide a new, non-destructive, rapid and flexible process analysis technique to operando monitoring the synthesis process of ionic liquids. The main research contents are as follows:(1) The relaxation characteristics T1/T2 of imidazole, pyridine, halogenated alkanes and corresponding ionic liquids were systematically measured, and then the low-field nuclear magnetic resonance imaging technology was chosen as a process analysis tool to study operando the ionic liquid synthesis process. Taking the synthesis of [C4mim]Br as an model reaction, we established the methods for qualitative and quantitative analysis of the components of the reaction system and validated it with in-situ infrared spectroscopy. The results were consistent. (2) In-situ studies on [C4mim]Br using low-field nuclear magnetic resonance imaging have shown that the higher the initial molar ratio of imidazole to bromobutane, the higher the reaction temperature and the faster the stirring speed, resulting in faster synthesis speed. The calculated second order kinetic rate constant k (0.042 to 1.378 mol-1·L·h-1) and apparent activation energy EA (72 kJ/mol) were in accordance with the literatures. The phase behavior of the [C4mim]Br synthesis process was visualized based T1-weighted images with LF-MRI, and it was found that the whole system underwent phase separation when the yield of ionic liquid was 40 mol%, coalescence and phase inversion, and finally the ionic liquid flowed from the upper layer to the bottom of the tower at 32℃, 1.2 mol ratio of BuBr/MIM.(3) The effects of halogenated alkane chain length, halogen element type and tertiary amine basicity on alkylation of tertiary amine/halohydrocarbon synthetic ionic liquids were systematically studied using low-field MRI system. The results show that the longer the alkyl carbon chain, the slower the synthesis rate; the greater the electronegativity of the halogen element of the halogenated alkane, the faster the synthesis rate of the ionic liquid, such as BuI>BuBr>BuCl. In addition, the basicity of tertiary amine also has a great influence on the synthesis rate, for example, the synthesis rate of [C4py]Br is far less than [C4mim]Br, and the rate constants are 0.047 and 0.807 (mol/L)-1·h-1, respectively.
|刘亚迪. 低场核磁共振成像原位研究离子液体合成过程[D]. 中国科学院大学,2020.|
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